openvpn-auth-oauth2 returns FUNC_SUCCESS on client-deny, allowing unauthenticated VPN access_CVE-2026-41070

{
    "lastseen": "",
    "description": "openvpn-auth-oauth2 is a plugin/management interface client for OpenVPN server to handle an OIDC based single sign-on (SSO) auth flows. From version 1.26.3 to before version 1.27.3, when openvpn-auth-oauth2 is deployed in the experimental plugin mode (shared library loaded by OpenVPN via the plugin directive), clients that do not support WebAuth/SSO (e.g., the openvpn CLI on Linux) are incorrectly admitted to the VPN despite being denied by the authentication logic. The default management-interface mode is not affected because it does not use the OpenVPN plugin return-code mechanism. This issue has been patched in version 1.27.3.",
    "published": "2026-05-08T15:14:46.186Z",
    "modified": "2026-05-08T16:05:34.531Z",
    "type": "cve",
    "title": "openvpn-auth-oauth2 returns FUNC_SUCCESS on client-deny, allowing unauthenticated VPN access",
    "source": "GitHub_M",
    "references": "https://github.com/jkroepke/openvpn-auth-oauth2/security/advisories/GHSA-246w-jgmq-88fg\nhttps://github.com/jkroepke/openvpn-auth-oauth2/commit/36f69a6c67c1054da7cbfa04ced3f0555127c8f2",
    "id": "CVE-2026-41070",
    "bulletinFamily": "",
    "cwe": [
        "CWE-287"
    ],
    "cvelist": null,
    "sourceData": "jkroepke openvpn-auth-oauth2 >= 1.26.3, < 1.27.3",
    "sourceHref": "",
    "cvss": {
        "score": 10,
        "severity": "CRITICAL",
        "vector": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:N",
        "version": "3.1"
    },
    "cvss2": [],
    "cvss3": {
        "version": "",
        "vectorString": "",
        "baseScore": 0,
        "baseSeverity": "",
        "attackVector": "",
        "attackComplexity": "",
        "privilegesRequired": "",
        "userInteraction": "",
        "scope": "",
        "confidentialityImpact": "",
        "integrityImpact": "",
        "availabilityImpact": "",
        "cvssV3": {
            "version": "",
            "vectorString": "",
            "baseScore": 0,
            "baseSeverity": "",
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            "privilegesRequired": "",
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            "confidentialityImpact": "",
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        }
    },
    "href": "",
    "category_name": "CVE",
    "post_link": "",
    "product": "openvpn-auth-oauth2",
    "version": ">= 1.26.3, < 1.27.3",
    "vendor": "jkroepke",
    "ai_description": "Unauthenticated VPN access due to incorrect handling of client authentication",
    "ai_severity": "Critical",
    "ai_vendor": "jkroepke",
    "ai_product": "openvpn-auth-oauth2",
    "ai_version": "1.26.3-1.27.3",
    "ai_score": 10
}